Saving water is a major driver for introducing electronics into modern agriculture. Intelligent water management is based on weather information but also the moisture of the soil. A network of wireless moisture sensors can provide the information needed to supply the right amount of water to plants in a specific area.
Capacitive soil moisture sensors determine the amount of soil moisture or water content of the soil by measuring changes in capacitance. The sensor can be made of a simple PCB with two electrodes that are covered by resin to protect against corrosion.
Figure 1: Diagram Moisture
ScioSense signal conditioner PCAP04 measures the capacitance by means of a discharge-time measurement, based on a precision time-to-digital conversion. This allows very short measurement times and therefore very low power consumption.
With only a few microampere such solutions are perfectly suited to build battery-driven, wireless sensor modules.